I reached out to someone more familiar with this hardware and we all agree that you should be able to use the system as you'd like once it is otherwise decommissioned. Here's what we are able to share:
I would reset BIOS, shut it down, and unplug power sources from the chassis (if possible).
See pg 24.
BIOS Reset:
https://$BMC_IP/redfish/v1/Systems/1/Bios/Actions/Bios.ResetBios
POST a reset of the BIOS attributes to default values. After POST, please reset system to set values to BIOS.
If the above does not work, I recommend flashing BIOS.
I hope this is helpful!
Community Manager \\ NetApp